Origin of the Expression "Know the Ropes"

This is an old sailing expression. In the past, the rigging of large ships used to be made up of many miles of rope, divided into hundreds of separate lengths, and each of these with a separate name an purpose.
To know the functions of all these ropes took years of sailing experience. Only old see dogs knew the ropes, and so when we say that someone knows the ropes, we mean  that someone has a lot of practical experience.